all of them have some form of learning curve, the most novice friendly is fritzing, which I dont really care for due to its workflow

you start with a virtual breadboard (which is where most people stop and its a pain in the butt to read) from there it will lay out a schematic based on that, then you can do boards from there. to me the breadboard part is just another step ... especially if I already have it on a real breadboard. its also tied into their fab service, wich IMO is expensive.

http://fritzing.org/

express PCB has free software as well and its pretty easy to pick up, no goofy breadboard but its also tied into their fab service (also expensive)

http://www.expresspcb.com/index.htm

KiCad is an open source EDA, and when it works it is not that much of a pain in the butt, it spits out standard files that can be used with any fab, but its wonky and often times somewhat broken, I used to use it but I just cant stand doing a bunch of work for it to puke out on me, examples vary with version but from random crashes to erasing half my crap if I want to print it ... ugh

http://www.kicad-pcb.org/display/KICAD/KiCad+EDA+Software+Suite

GEDA is a toolkit that makes up a EDA, not much experience with ithttp://www.geda-project.org/

Eagle is a commercial grade package that gives away a restricted version that is very popular with hobbiesthttp://www.cadsoftusa.com/

SpikeUK2564

As a side issue, I have a very troublesome professionally made, 20 year old control board, which has caused me endless problems (the manufacturer can't offer support). Can I use any of these programs to create a schematic of the traces and components of this board, to try and work out how the board works. I have found that there are some ICs on the board that aren't in the library of these programs. How do I get around that? The part numbers are visible. Thanks.

you can use any of them, I would recommend eagle, since its pretty serious and there are tons of tutorials on it ... and once you learn one of the more serious ones you can pretty much use any of them with little change outside of figuring out where stuff is.

as far as missing components go, you can search the interwebs for them, or you can make a schematic symbol for them. No matter what you use its going to be missing something, thats the way it is. Parts are obsoleted every day, and manufactures are releasing new parts heavy and frequently.

With any half-decent schematic capture program you can design your own components, if you can get the data sheets for the components you are in business.

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Can I use any of these programs to create a schematic of the traces and components of this board,

None of them will do it for you, but you can reverse engineer the board by looking at the traces and redrawing the circuit yourself. Just hope that it's only a 1- or 2-layer board

If it's 20 years old I would suggest however that physically replicating it is not the way to go, just replicate the functionality with newer hardware. But that depends on it's exact function, it may be that there are no better chips even now, especially if there's no CPU involved